Formula variables
- Battery kWh is the nominal vehicle battery capacity entered by the user.
- Start and target SOC are state-of-charge percentages.
- Charger kW is the effective charging power used for the estimate.
- Charging efficiency is the entered grid-to-battery efficiency percentage.
Assumptions
- Charging time is calculated from the battery energy added and the entered charger kW.
- Charging efficiency accounts for grid-to-battery losses as an editable planning assumption.
- Actual time can be longer because of vehicle onboard-charger limits, charge taper, battery temperature, and starting conditions.
- This calculator does not size the EV branch circuit, breaker, conductor, receptacle, load-management device, or service capacity.
Examples
Typical overnight Level 2 session. A 75 kWh EV charging from 20 percent to 80 percent at 7.7 kW with 90 percent efficiency estimates about 6.49 hours.
High state-of-charge review. Charging above roughly 90 percent can taper on many vehicles, so the simple energy-time estimate may be optimistic.